1. Field of the Invention
The present invention relates to a packaging for a photographic film cassette, more particularly to a packaging suitable for packaging a cassette of which rotation of a spool causes a leader to advance outward from the cassette.
2. Description Related to the Prior Art
A conventional photographic film cassette (hereinafter referred to as a cassette) has a metal cassette shell, which rotatably contains a plastic spool around which a photographic filmstrip (hereinafter referred to as film) is wound. The cassette shell is constituted of a cylinder made of a metal sheet and caps fitted on its both ends of the cylinder. A leader of the photographic film protrudes from the cassette even before the photographic film is used. This cassette is packaged in a cap-fitted cylindrical, moisture-proof plastic case called a P case, and overwrapped in a carton for retail sale.
Also, it is known to utilize a photographic film cassette wherein the photographic film is positioned so that the leader does not protrude from a cassette shell prior to loading the cassette in a camera. Such a cassette is described in U.S. Pat. Nos. 4,834,306 and 4,846,418. Simple film-advancing mechanisms of the camera are used with this type of cassette, and include a construction which rotates a spool to unwind the photographic film, thereby causing the leader to move through a passageway for the photographic film and thereby exit from the cassette. This cassette is advantageous over the other conventional cassette discussed above, because the photographic film can be shielded from light more reliably, and the cassette can be loaded in the camera with greater ease.
The conventional packaging constituted of the P case and the carton, however, is disadvantageous. In particular, its double structure is costly and requires the troublesome operation of double removal, i.e., removal of the P case from the carton, and removal of the cassette from the P case. When using a P case for the above-described leader-advancing cassette, the leader may be inadvertently advanced outward from the cassette due to shock or vibration during mass transportation or while being carried by the user. The cassette under such a condition cannot be loaded in a camera if the camera is adapted for use only with a leader-advancing cassette which is loaded in a state without protrusion of the leader. In a leader-advancing cassette, smooth leader advancement requires that the turns of the photographic film are wound regularly around a spool before advancement. Rotation of the spool due to the shock or vibration, however, causes the film turns to be irregular within the cassette shell. Accordingly, the leader might not reliably exit from the cassette.
Japanese Utility Model Laid-open Publication No. 63-165650 proposes an attachment of a seal to a spool which partially projects from the cassette shell, so that the spool cannot rotate relative to a cassette shell before the photographic film is exposed. However, this structure is difficult to apply to a leader-advancing cassette, because such a cassette generally has a structure such that ends of a spool do not project from, but are flush with, or retracted from, the shell end faces. Such a construction avoids inadvertent manual rotation of the spool, e.g., when a user applies his fingers thereto.